I need to send multiple tasks to Grand Central Dispatch to run. Some tasks will finish first, while some will finish last.
How do I know all my tasks in Grand Central Dispatch finished?
Should I use a counter to record the number of tasks finished? Any smarter method?
You can achieve this using GCD using DispatchGroup in swift 3. You can get notified when all tasks are finished.
let group = DispatchGroup()
group.enter()
run(after: 6) {
print(" 6 seconds")
group.leave()
}
group.enter()
run(after: 4) {
print(" 4 seconds")
group.leave()
}
group.enter()
run(after: 2) {
print(" 2 seconds")
group.leave()
}
group.enter()
run(after: 1) {
print(" 1 second")
group.leave()
}
group.notify(queue: DispatchQueue.global(qos: .background)) {
print("All async calls completed")
}
You can use dispatch groups to be notified when all tasks completed. This is an example from http://cocoasamurai.blogspot.com/2009/09/guide-to-blocks-grand-central-dispatch.html
dispatch_queue_t queue = dispatch_get_global_queue(0,0);
dispatch_group_t group = dispatch_group_create();
dispatch_group_async(group,queue,^{
NSLog(@"Block 1");
});
dispatch_group_async(group,queue,^{
NSLog(@"Block 2");
});
dispatch_group_notify(group,queue,^{
NSLog(@"Final block is executed last after 1 and 2");
});
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